A 1/2 HP sump pump runs at about 1,050 W but needs up to 2,150 W to start. On its own that means a 3,000 W class generator; with a full-size fridge on too, 3,500 W class. A 1/3 HP pump needs 1,600 W to start.
Start with a common setup
Pick the closest match, then fine-tune the list below.
Fridge, sump pump, furnace fan, five lights and the Wi-Fi router. Change anything below.
Your 3,345 W peak + 20% margin = 4,014 W, rounded up to the next 500 W.
Running
2,245W
Everything on at once
Peak
3,345W
+1,100 W when the sump pump starts
Size4,500 WRunning2,245 WPeak3,345 W
Of the 11 generators we track:1 fits well2 fit, but tight8 won’t work
Honda generatorEU7000iS
Comfortable
Running
5,500 W
Starting
7,000 W
Outlets
120/240V
Rated 5,500 W covers your 3,345 W peak plus 20%.
Published runtime: 6.4 h at full rated load · 16 h at 1/4 load · 5.1 gal tank. At your load (41%): between 6.4 h and 16 h per tank (estimate between the published points).
Starting output of 3,000 W is below your 3,345 W peak.
Published runtime: 6.9 h at full rated load · 19.6 h at 1/4 load · 3.4 gal tank. At your load (80%): between 6.9 h and 19.6 h per tank (estimate between the published points).
refrigerator: 1.1–2.1 kWh a day (not sure, ENERGY STAR/DOE ranges), not its nameplate watts. Hours per day: sump pump 2 h, furnace fan 12 h, LED bulb 6 h, Wi-Fi router or modem all day. These are example estimates; change them under “Edit watts and hours”.
Of the 11 power stations we track:3 fit well1 fits, but tight7 won’t work
Jackery power stationHomePower 3000
Fits
Capacity
3,072 Wh
Continuous
3,600 W
Surge
7,200 W
3,600 W continuous covers your 2,245 W load plus 20%.
Verdicts use a 20% margin over peak. Add the rest of your list in the planner above.
Battery backup sump systems are a different product
A “sump pump battery backup” is usually a second, 12V pump with its own battery that takes over when the main pump loses power. It isn’t sized in the same way as a generator or portable power station, and we don’t cover those systems here.
If you plan to run your existing 120V pump from a portable power station, its surge output must cover the pump’s start: 2,150 W for a 1/2 HP pump. 9 of the 11 stations we track can.